This invention relates to the production of a spray of atomized particles and subsequently to imparting direction to the spray, and might find application in the production of either a layer or coating on a substrate, billet, tube or irregular section article.
The usual procedure is to atomize a stream of liquid by means of a high pressure gas to form a stream of atomized droplets that is directed onto a substrate or former, but it is also possible, especially with metals, to use wire or powder as the feedstock for producing a stream of droplets.
A wide range of such processes and materials have been proposed, but the process has been applied particularly advantageously to the sprayforming of metals. This process was devised in 1968 and has the capability of making a wide range of semi-finished products having improved properties. The products comprise plate, sheet and strip e.g. of high silicon steel, hollow and solid billets, tubes and rings as well as laminated products and matrix composites. In order to produce the particular shapes required it is usually necessary to move the substrate or former in an appropriate manner and at the same time to deflect the stream of atomized particles. The latter procedure is particularly important in ensuring that the process is operated with the highest efficiency with the lowest possible overspray and that the product is as near as possible to the final shape required.
We have found that the most efficient and reliable way of deflecting the stream of atomized particles is by pneumatic means i.e. using a secondary stream or streams of gas, usually inert gas, to deflect the primary atomized spray causing it to assume the required position. This procedure is herein referred to as `scanning`. Ways of carrying out this procedure are described in GB 1455862 and GB 2129249.
Turning firstly to the external programming of pneumatic scanning atomizers embodying rotary valves for programming.